DUXBURY — A Duxbury man pleaded not guilty Thursday to having sex with a 15-year-old girl.

Patrick M. Sherman, 19, is facing a charge of felony sexual assault on a victim under 16 years old. If convicted, he faces a maximum sentence of 20 years and a $10,000 fine.

According to the Vermont State Police affidavit, state police were responded to a reported domestic assault in Duxbury last month.

When interviewed by state police, Sherman said he and the girl had been dating for a year and had been having sex since the first week they met. He said when they first met, the girl told him she was 17 years old. He later found out how old the girl really was, but the relationship continued.

The girl also was interviewed by state police and she said she and Sherman had been dating since February. The girl said Sherman told her he was 18 years old and she had told him up front that she was 15 years old.